examples/msg/bittorrent/tracker.c

   1 /* Copyright (c) 2012. The SimGrid Team.
   2  * All rights reserved.                                                     */
   3
   4 /* This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the license (GNU LGPL) which comes with this package. */
   6 #include "tracker.h"
   7 #include <msg/msg.h>
   8 #include <xbt/RngStream.h>
   9
  10 static void task_free(void *data);
  11
  12 XBT_LOG_NEW_DEFAULT_CATEGORY(msg_tracker, "Messages specific for the tracker");
  13 /**
  14  * Tracker main function
  15  * @param argc number of arguments
  16  * @param argv arguments
  17  */
  18 int tracker(int argc, char *argv[])
  19 {
  20   int i;
  21
  22   RngStream stream = RngStream_CreateStream("tracker");
  23
  24   //Checking arguments
  25   xbt_assert(argc == 2, "Wrong number of arguments for the tracker.");
  26   //Retrieving end time
  27   double deadline = atof(argv[1]);
  28   xbt_assert(deadline > 0, "Wrong deadline supplied");
  29   //Building peers array
  30   xbt_dynar_t peers_list = xbt_dynar_new(sizeof(int), NULL);
  31
  32   XBT_INFO("Tracker launched.");
  33
  34   msg_comm_t comm_received = NULL;
  35   msg_task_t task_received = NULL;
  36
  37   while (MSG_get_clock() < deadline) {
  38     if (comm_received == NULL) {
  39       comm_received = MSG_task_irecv(&task_received, TRACKER_MAILBOX);
  40     }
  41     if (MSG_comm_test(comm_received)) {
  42       //Check for correct status
  43       if (MSG_comm_get_status(comm_received) == MSG_OK) {
  44         //Retrieve the data sent by the peer.
  45         tracker_task_data_t data = MSG_task_get_data(task_received);
  46         //Add the peer to our peer list.
  47         if (!is_in_list(peers_list, data->peer_id)) {
  48           xbt_dynar_push_as(peers_list, int, data->peer_id);
  49         }
  50         //Sending peers to the peer
  51         int next_peer;
  52         int peers_length = xbt_dynar_length(peers_list);
  53         for (i = 0; i < MAXIMUM_PAIRS && i < peers_length; i++) {
  54           do {
  55             next_peer =
  56                 xbt_dynar_get_as(peers_list,
  57                                  RngStream_RandInt(stream, 0, peers_length - 1),
  58                                  int);
  59           } while (is_in_list(data->peers, next_peer));
  60           xbt_dynar_push_as(data->peers, int, next_peer);
  61         }
  62         //setting the interval
  63         data->interval = TRACKER_QUERY_INTERVAL;
  64         //sending the task back to the peer.
  65         MSG_task_dsend(task_received, data->mailbox, task_free);
  66         //destroy the communication.
  67       }
  68       MSG_comm_destroy(comm_received);
  69       comm_received = NULL;
  70       task_received = NULL;
  71     } else {
  72       MSG_process_sleep(1);
  73     }
  74   }
  75   //Free the remaining communication if any
  76   if (comm_received) {
  77     MSG_comm_destroy(comm_received);
  78   }
  79   //Free the peers list
  80   xbt_dynar_free(&peers_list);
  81   //Free the RngStream object.
  82   RngStream_DeleteStream(&stream);
  83
  84   XBT_INFO("Tracker is leaving");
  85
  86   return 0;
  87 }
  88
  89 /**
  90  * Build a new task for the tracker.
  91  * @param issuer_host_name Hostname of the issuer. For debugging purposes
  92  */
  93 tracker_task_data_t tracker_task_data_new(const char *issuer_host_name,
  94                                           const char *mailbox, int peer_id,
  95                                           int uploaded, int downloaded,
  96                                           int left)
  97 {
  98   tracker_task_data_t task = xbt_new(s_tracker_task_data_t, 1);
  99
 100   task->type = TRACKER_TASK_QUERY;
 101   task->issuer_host_name = issuer_host_name;
 102   task->mailbox = mailbox;
 103   task->peer_id = peer_id;
 104   task->uploaded = uploaded;
 105   task->downloaded = downloaded;
 106   task->left = left;
 107
 108   task->peers = xbt_dynar_new(sizeof(int), NULL);
 109
 110   return task;
 111 }
 112
 113 /**
 114  * Free a tracker task that has not succefully been sent.
 115  * @param data Task to free
 116  */
 117 static void task_free(void *data)
 118 {
 119   tracker_task_data_t task_data = MSG_task_get_data(data);
 120   tracker_task_data_free(task_data);
 121   MSG_task_destroy(data);
 122 }
 123
 124 /**
 125  * Free the data structure of a tracker task.
 126  * @param task data to free
 127  */
 128 void tracker_task_data_free(tracker_task_data_t task)
 129 {
 130   xbt_dynar_free(&task->peers);
 131   xbt_free(task);
 132 }
 133
 134 /**
 135  * Returns if the given id is in the peers lsit
 136  * @param peers dynar containing the peers
 137  * @param id identifier of the peer to test
 138  */
 139 int is_in_list(xbt_dynar_t peers, int id)
 140 {
 141   unsigned i;
 142   int elm;
 143   xbt_dynar_foreach(peers, i, elm) {
 144     if (elm == id) {
 145       return 1;
 146     }
 147   }
 148   return 0;
 149 }